1. Field
The present disclosure relates to a novel promoter of Corynebacteria, a vector including the promoter, a host cell comprising the vector, and a method of expressing a gene using the host cell.
2. Description of the Related Art
Species of the genus Corynebacterium, or corynebacteria, particularly Corynebacterium glutamicum, is a gram-positive bacteria which is used to produce amino acids, such as glutamate, lysine, and threonine. Corynebacterium glutamicum grows under relatively simple culture conditions, may be cultured at a high concentration compared to Escherichia coli, and has a stable genetic structure, thus having a low possibility of mutation occurrence. Also, since Corynebacterium glutamicum is nonpathogenic and does not produce spores, the strain does not have a malignant influence on the environment and, thus, may be used as an industrial strain.
Corynebacterium glutamicum is an aerobe, and its growth is ceased under anaerobic conditions or when oxygen supply is stopped. Under anaerobic conditions, metabolic processes of Corynebacterium glutamicum other than those necessary in producing minimum energy for survival are ceased, and lactic acid, acetic acid, succinic acid etc. are produced and released from Corynebacterium glutamicum. In this regard, metabolism of Corynebacterium glutamicum is focused on producing and releasing the desired products under anaerobic conditions, and growth may be less of a concern, and, thus, bacteria may be maintained at a high concentration.
A promoter is a DNA region to which an RNA polymerase binds to initiate the transcription of a gene which is operably linked to the promoter. The strength and conditions of the gene expression are determined, at least in part, by the promoter sequences and/or length of the promoter, whether RNA polymerase and transcription factors bind the promoter sequences, and the strength of the binding. The transcription factors include modulator proteins, by which gene expressions are modulated only under particular environmental conditions, such as growth state of cells, oxygen requirement, and temperature.
Industrial application of microorganisms is often based on the overexpression of desired genes. In the case of prokaryotes, most genes may be overexpressed when a strong promoter is used, and thus it is important to search for a strong promoter that may be well expressed under given production conditions. In particular, although Corynebacteria have long been used as industrial microorganisms, studies on anaerobic fermentation of Corynebacteria have only just begun. Thus, finding a promoter that functions at a satisfactory level under anaerobic conditions is necessary.